You may have heard some people recommend adding dishwashing liquid to your windscreen washer reservoir.
It sounds logical at first. If dishwashing soap can cut through grease, it can surely help clear the grime on your windscreen. But there are negative effects to doing this.
It is easy to clean the windscreen during a heavy downpour.
However, there are those sunny mornings when you get in your car and have to look out through a glass spotted with bird droppings. Usually they are stuck like glue and even several sweeps of your wiper with the washer continuously spraying will not remove them.
The surest way to get your windscreen clean is by using a dedicated car shampoo when you wash your vehicle.
If not, a use a cloth and copious amounts of water. Most contaminants, including bird droppings, need to be soaked in water or windscreen washer fluid before they start to break away. The latter is even more effective.
Good windscreen washer additives are available from most petrol stations and car accessories sections of supermarkets. They all contain some percentage of alcohol, so read the instructions on how much to mix with the water in your reservoir.
Remember that when you use the water jets, some amount of the liquid eventually flows onto the car body. Hence, excessively strong washing solutions could streak your paintwork.
A windscreen washer reservoir containing any amount of household detergent must never be used.
These liquids are formulated to remove grease and oils from ceramics, stainless steel and glass. Most of these are therefore detrimental to wax and even the clear coat that protects your paint.